WM8974GEFLSLASHV datasheet(45/87 Pages) WOLFSON

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Production Data

WM8974

PD Rev 4.2 March 2007

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

DAC2MONO

Output of DAC to mono mixer input

0 = not selected

1 = selected

BYP2MONO

Bypass path (output of input boost stage) to

mono mixer input

0 = non selected

1 = selected

AUX2MONO

Output of Auxillary amplifier to mono mixer

input:

0 = not selected

1 = selected

R56

Mono mixer control

MONOMUTE

0=No mute

1=Output muted. During mute the mono

output will output VMID which can be used

as a DC reference for a headphone out.

R40

Bypass path

attenuation control

MONOATTN

Attenuation control for bypass path (output

of input boost stage) to mono mixer input

0 = 0dB

1 = -10dB

Table 41 Mono Mixer Control

ENABLING THE OUTPUTS

Each analogue output of the WM8974 can be separately enabled or disabled. The analogue mixer

associated with each output has a separate enable. All outputs are disabled by default. To save

power, unused parts of the WM8974 should remain disabled.

Outputs can be enabled at any time, but it is not recommended to do so when BUFIO is disabled

(BUFIOEN=0), as this may cause pop noise (see “Power Management” and “Applications

Information” sections).

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

BUFIOEN

Unused input/output tie off buffer enable

BUFDCOPEN

Output stage 1.5xAVDD/2 driver enable

Power

management 1

BIASEN

Analogue amplifiers bias enable

SPKMIXEN

Speaker Mixer enable

MONOMIXEN

Mono mixer enable

SPKPEN

SPKOUTP enable

SPKNEN

SPKOUTN enable

Power

management 3

MONOEN

MONOOUT enable

Note:

All “Enable” bits are 1 = ON, 0 = OFF

Table 42 Output Stages Power Management Control

UNUSED ANALOGUE INPUTS/OUTPUTS

Whenever an analogue input/output is disabled, it remains connected to a voltage source (either

AVDD/2 or 1.5xAVDD/2 as appropriate) through a resistor. This helps to prevent pop noise when the

output is re-enabled. The resistance between the voltage buffer and the output pins can be

controlled using the VROI contol bit. The default impedance is low, so that any capacitors on the

outputs can charge up quickly at start-up. If a high impedance is desired for disabled outputs, VROI

can then be set to 1, increasing the resistance to about 30k

Ω.

WM8974GEFL/V Datasheet(PDF) 45 Page - Wolfson Microelectronics plc

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